What's the best non-surgical long term treatment option for nasolabial folds and marionette lines? (Photos)

Thank you for sharing your question and posting your photos. You would achieve improvement in the smile lines with fillers. I don't think thread lifting (which I like) would help much for your particular lines. Make an appointment for in-person, comprehensive evaluation and discussion of potential options with an experienced oculoplastic surgeon. Good luck!

The results that you have obtained from your prior treatments are quite good so I would exercise caution in chasing perfection.  The lines in your face that you are concerned with can be treated with a hyaluronic acid filler but I would caution against using any permanent fillers in this area.  The results that you expect to obtain, complete alleviation of the smile lines, are unfortunately unlikely to be achieved regardless of the number of treatments you perform on this area.  A reversible hyaluronic acid filler will provide the exact same result as a permanent or semi permanent filler with considerably more safety especially if the filler doesn't look quite right immediately, one week, one month, or at one year.  One other guarantee is that your face is going to change as you age and the permanent product that was placed in a very obvious place on your face will not. So what looked good today may look awkward or obvious in a few years.

From you photos, your cheeks look absolutely fine and you do not have prominent smile folds nor marionette lines. It appears, in fact, that you have very fine smile lines, which can be quite easily and safely treated with a cohesive, hyaluronic acid-based filler, such as Belotero Balance. As to permanent fillers, I can only emphasize that permanent fillers can translate into permanent complications, which can appear immediately after treatment or in five, ten or even twenty years afterward.  And besides, even if you were fortunate and escaped this, you need to take into consideration that even if the results with permanent fillers are pleasing at first, those same results may not look good or appropriate five or ten years down the road when age-related changes take place around the filler; i.e. what may look fine today may look bizarre in ten years when the rest of the face ages. Finally, as to absorbable barbed threads, a recent February, 2019 study published in Aesthetic Surgery Journal  found that the adverse complication rate was 34% and the improvement "noticeabley declined by six months and was absent by one year."  Make sure that you do your due diligence and consult with a board certified aesthetic physician and also keep in mind to place physician credentials over cost when deciding how best to proceed. Best of luck to you.